A conventional cutting tool is disclosed in Patent Literature 1. More specifically, Patent Literature 1 discloses a cutting tool for face grooving, which is used for grooving an end face of a workpiece, and a configuration using a member called an adjustment blade to adapt to various widths of grooves to be machined. The adjustment blade is a plate member which partly curves. To the curved plate portion, a cutting insert in the form of a grooving insert is removably mounted. The adjustment blade is fastened to the member in a shank side with two bolts.